1. Field of the Invention
The present invention relates to an antenna apparatus that includes an element member made of punched sheet metal.
2. Description of the Related Art
In recent years and continuing, much attention is being focused on UWB as a wireless communications technology enabling radar positioning and broadband communications, for example. In 2002, the U.S. Federal Communication Commission (FCC) approved usage of the UWB within a frequency band of 3.1-10.6 GHz.
The UWB is a wireless communications technology that involves transmitting pulse signals across a very wide frequency band. Therefore, an antenna used for UWB communication has to be capable of transmitting and receiving signals within a very wide frequency band.
It is noted that in “An Omnidirectional and Low-VSWR Antenna for the FCC-Approved UWB Frequency Band” by Takuya Taniguchi and Takehiko Kobayashi (The 2003 IECIE General Conference, B-1-133), an antenna adapted for use at least in the FCC-approved frequency band of 3.1-10.6 GHz is disclosed that comprises a ground plane and a feed element.
However, a conventional broadband antenna apparatus is constructed by arranging a cone-shaped or tear-shaped feed element on a flat ground plane. The antenna apparatus constructed in such a manner is rather large so that techniques for miniaturizing and flattening the antenna apparatus are in demand.
Also, with respect to technology related to a loop antenna adapted for low frequency band communication, Japanese Laid-Open Patent Publication No. 2000-196327 discloses an antenna apparatus that has a flexible substrate on which an element is formed by a conductive pattern.
However, the above-disclosed antenna apparatus uses a flexible substrate and also requires a connector for establishing connection with the exterior. Such an antenna apparatus has a relatively large number of components and the process for fabricating the antenna apparatus includes a large number of process steps so that low productivity and high manufacturing costs have been a problem.